JUSTIFICATION FOR BITUMEN RUBBER BINDER IN EXTREME CLIMATES SUCH AS SOUTH AFRICA

Bitumen rubber chip and spray seals have been used successfully in South Africa since 1982 and mostly in road rehabilitation projects. The main advantage of bitumen rubber (B-R) seals extra over a standard binder is its superior waterproofing as well as its ability to prevent reflective cracks breaking through the newly placed chip seals or asphalt overlays and its longevity. This paper concludes that the higher spray rates together with the better rheological properties of bitumen rubber modified binders provide the following additional benefits: widening of working temperature range (Fraass freezing point up to softening point); reducing temperature sensitivity; longevity due to anti-oxidants in tyre buffings; better adhesion; stress absorbing qualities; better Average Least Dimension (ALD) aggregate stands because of high B-R stiffness; lesser stone embedment because of higher softening point; resistance to binder absorption; lesser pre-treatments; and superior elasticity and fatigue. For the covering abstract see ITRD E121480.